1. Field of the Invention
This invention relates to a handle assembly for manual operation of electric switches, and more particularly to an operator-manipulable handle assembly for manually operating high-voltage switches which is easy to use and convenient to manufacture, which requires the application of only reasonable force, and which is virtually tamper-proof and prevents unauthorized operation of the switches.
2. Description of the Prior Art
High-voltage switches and switchgear containing such switches of various types are well known. High-voltage switchgear, for the purposes of the present invention, may be generally described as including one or more high-voltage switches contained within a metal enclosure. Each switch within the enclosure may have connected in electrical series therewith a high-voltage fuse or other protective device. The switches themselves are typically interrupting switches, but may be other types. Interrupting switches have the capability of interrupting magnetizing or normal load currents upon the opening thereof and may, at times, have fault closing ratings, that is, the ability to close while a fault condition exists.
In general, a high-voltage switch includes one or more stationary contacts, and a movable contact or blade. The switch is closed when the blade engages the stationary contacts and is open when the blade is disengaged from the stationary contacts. The blade may move in a rotative fashion and, if more than one switch is present within the enclosure, the blades of all switches may be simultaneously rotated between the open and closed positions by the rotation of a common drive member or strut to which all of the blades are attached. The switch blade may also be reciprocable, that is, linearly movable toward and away from the stationary contacts.
A wide variety of manual operating handles to operate high-voltage switches are well known. Such handles are often rotatable from the exterior of the enclosure in order to operate the switches. In this way, the switches may be operated without the need for entering the enclosure. After the operation of the switches within the enclosure; i.e., after the switches are either fully opened or fully closed, it is usually desired that the handle have the capability of being locked. Locking prevents the unauthorized operation of the switches. Also, it is often desired that the handle or switches be selectively immobilized by a so-called key interlock. Such an interlock can be manipulated to free the handle and switches for movement only when its key is present therein. The key is available for this purpose only if other apparatus (other switches, etc.) is in some selected condition which releases the key. This ensures that the switches and the other apparatus are operated in an appropriate sequence and have appropriate relative conditions.
Often, the switches are not operated directly by rotation of the handle. Rather, it is often desirable to provide a stored-energy mechanism, the condition of which is affected by rotation of the handle. The stored-energy mechanism operates the switches rapidly in a manner not dependent upon the speed of rotation of the handle. These stored-energy operating mechanisms often require a high degree of mechanical effort to store energy therein. Thus, in addition to its ability to be locked in the positions it occupies when the switches are fully opened or fully closed, an operating handle must usually have a substantial length so that only a reasonable amount of force is required to rotate the handle, thus operating the stored-energy mechanism and the switches.
Typical operating handles, until now, have usually included rotative handle members external of the enclosure, the majority of the handle being fully exposed to the elements at all times unless covers or the like are provided. It would be desirable to provide an operating handle, the parts of which are not fully, directly exposed to the elements. Further, known exposed handles usually have unsightly "high profiles," i.e., they protrude substantially away from the surface of the enclosure even when locked. This leads to covers for such handles also having high profiles and, if covers are not used, permits unauthorized persons or vandals to apply prying forces to the handles which may lead to improper and unauthorized operation of the switches. It is a desirable goal to provide a "low profile" handle which does not protrude from the enclosure in an unsightly manner and to which prying forces cannot be applied in an attempt to operate the switches without authorization.
Accordingly, a primary object of the present invention is to provide an improved operating handle assembly for apparatus, such as electric switches, which may be locked when the switches are fully closed to prevent unauthorized operation thereof, which has a length sufficient to require only the application of reasonable force in order to operate the switches, which is not fully directly exposed to the elements, which may conveniently be associated with a key interlock, which has a low profile, and which is convenient to manufacture.